Ebonite is a known rubber compound containing a high sulfur content, typically compounded with 30 to 50% by weight sulfur, having a high Shore A hardness. Ebonite compounds have been used in tank linings for chemical products and in other applications where hardness and impermeability are desired. For example, U.S. Pat. No. 4,469,729 discloses that in the past, for flexible articles such as belts, hoses, and diaphragms, the inner surface of the article was harden by ebonite formation. This was done to improve wear resistance, reduce friction, and provide for a barrier effect.
U.S. Pat. No. 5,222,770 discloses a high-pressure hydraulic hose. The multi-layered hose has an inner layer, an intermediate insulation layer, and an outer layer. Between the layers are several conductive layers. The inner, intermediate, and outer layers may be rubber or ebonite.
While ebonite has been used as an alternative to rubber layers in various articles, the presently disclosed invention is directed towards previously unappreciated benefits of ebonite in an article.